Another way to determine if your batch is the right consistency is take a handful of your thoroughly mixed ingredients and squeeze it in the palm of your hand. There should be a small amount of moisture that drips from your hand. At this point you are ready to start molding your container.
We use baskets, plant pots, cardboard boxes, Styrofoam containers and molds made of wood to make different shapes and sizes of containers. Your imagination is your only limit as to what your finished product will be. The next step is to line your mold with a thin plastic, an example would be dry cleaner plastic doubled. The thin plastic allows the cement mixture to go into all the corners of your mold. If you use a heavy plastic you may not get the true shape of the mold.
Now you can start building your container, one handful at a time. First you line the bottom of your mold with about 1 inch of hypertufa and then you start building the sides making sure the thickness is about 1 inch. Build the sides about 3 inches all around and then add another few inches until you have reached the top of your mold or the height you would like your container to be. You will need to smooth out and fine tune the surface trying to keep a consistent thickness of walls and base. Once you are satisfied with the container you need to let it sit in the mold for about 48 hours to allow the cement mixture to harden somewhat before you remove it from the mold. If you try to remove it too soon it will break apart when you take it out of the mold, but if you leave it too long in the mold it will be very difficult to remove as well. If you are making your containers in the summertime, cover them with plastic and do not set the container in full sun throughout the drying process as it will dry too quickly and not cure properly. You want the containers to dry slowly, which can take up to about 1 month, before they are completely dry.
Once you have taken the containers out of the mold it is time to scratch the outside of the surface with a metal brush, which takes away that smooth look created from the plastic liner and gives the pot a textured, natural look. At this point you also want to drill drainage holes in the container if you are planning on using it for a planter.
Once the container has dried completely, it is time to soak the container in water to wash away the lime residue from the cement. Most plants do not appreciate a strong concentration of lime, so we soak them for about 24 hours and then change the water and soak for another 24 hours. In this soaking we also brush the containers with a stiff brush to remove any loose particles. Now they must dry again for about 3-4 weeks. After they are dry they are ready to be planted. Plants of all types do very well in hypertufa containers as they do not heat up in the sun and they are porous which allows the roots of the plants to breath. The containers never fade, in fact the longer they are exposed to the elements the more natural the look to them. They will stand up to the heat, rain and cold.